Brain scan finds vegetative state patient conscious

A team led by neuropsychologist Dr Adrian Owen has reported on a patient who supposedly fulfilled all the criteria for a diagnosis of persistent vegetative state (PVS) but was found to have conscious awareness.

This seems a little confusing to me, as PVS is usually defined as where ‘higher’ cognitive abilities, such as awareness, are not present.

Unfortunately, I can’t read the article in full as I’m still away from home, but I suspect the diagnosis is usually based on observations of external signs of awareness, whereas Owen’s group used fMRI (a type of ‘brain scanning’) to look for changes in brain activation that would not necessarilly result in observable behaviour.

There’s a good write-up over at the BBC site with accompanying video, and for those with access to the full-text of the journal Science the original paper is available online.

This is similar to a recent study (covered previously on Mind Hacks) where researchers found evidence for similar sorts of ‘higher’ cognitive function in two patients in a ‘minimally conscious state‘.

It is likely, however, that all of these patients have suffered some problems with mental function, owing to extensive brain injury.

As psychology and neuroscience are able to measure brain function in more direct ways, rather than solely through observable behaviour, these sorts of coma-like states are likely to be found to be much more complex than previously thought.

However, neither of these conditions should be confused with ‘locked-in syndrome‘, where the cortex of the brain is largely undamaged, but selective damage to the brain stem means that the person cannot move his or her body and is often totally paralysed, despite being mentally intact.

One of the most powerful books I have ever read is the The Diving Bell and the Butterfly, written by the ex-editor of Elle magazine, who suffered a stroke and became ‘locked in’.

He wrote the book by indicating single letters with his only form of movement – an eye blink. The book is a transcendent description of his experience both before and after the onset of his condition.

Bauby died two days after the book was published but left the world with one of its most beautiful and unique literary works.

Link to BBC News story.
Link to abstract from Science.

2 Comments

  1. David Malone
    Posted September 8, 2006 at 7:15 pm | Permalink

    I once heard talk of using ocular microtremor to see if people’s brain stems were still working. I see from Wikipedia that there may also be links to how likely people are to recover from comas.

  2. Eric Thomson
    Posted September 8, 2006 at 10:50 pm | Permalink

    I am surprised this was published in Science, given that they didn’t do the crucial control. That is, as Pete Mandik suggested, give the same stimuli to someone under anesthesia (that we know is not conscious) and see if you get the same fMRI response. Their results could be all be due to unconscious stimulus-driven information processing.
    The paper in Science overstates things. They say:
    Moreover, her decision to cooperate with the authors by imagining particular tasks when asked to do so represents a clear act of intention, which confirmed beyond any doubt that she was consciously aware of herself and her surroundings.
    How, in a top-tier journal, did they allow phrases like “confirmed beyond any doubt” in such a first-pass study without proper controls?


Post a Comment

Required fields are marked *
*
*

Follow

Get every new post delivered to your Inbox.

Join 22,429 other followers